Clamping mechanism



March 1954 D. M. FAUST ET AL CLAMPING MECHANISM 2 Sheets-Sheet 1 Filed Dec. 26, 1961 In venfofif Donald M.Fcu s 1 Delano Wty l Y HH- .5.

M r 1964 D. M. FAUST ET AL CLAMPING MECHANISM 2 Sheets-Sheet 2 Filed Dec. 26, 1961 1 v a 1 I v I l1 ,MJ MM lnvenf'orr Donald M.'Fc1us *5 Delano Wlyhfi United States Patent 3,127,239 CLAMTPHQG MECHANEM Donald M. Faust, Estacada, and Delano Wight, Gresham, Greg, assignors to Cascade Manutacturing Company, Portland, Greg, a corporation of Gregor! Filed Dec. 26, 1961, Ser. No. 161377 5 (Ilaims. (ill. 294-88) This invention relates to clamping mechanism, and more particularly to clamping mechanism such as may be incorporated with a lift truck and the like, for clamping onto articles, and including a pair of opposed clamping arms and means mounting the arms whereby they may be shifted toward each other. The mechanism of the invention features a construction that accommodates on the one hand a relatively wide spacing of the arms (whereby a load of relatively large size may be clamped onto), and on the other hand a relatively close spacing of the arms (enabling the handling of small sized loads).

The invention as described herein relates to a lift truck attachment for handling paper rolls and similar cylindrical objects, such being referred to as a paper roll grab. Although the invention is described in connection with such a specific embodiment, obviously features of the invention may be incorporated in other types of clamping mechanisms, where the advantages provided by the construction contemplated are desirable features.

In clamping mechanism for a lift truck and the like, it is conventional to include a pair of arms that are relatively shiftable toward and away from each other between extended and retracted positions. Maximum versatility results if both arms are movably mounted, each for movement toward and away from the other. Thus, a lift truck attachment may comprise a frame with guides thereon, and mounted within these guides slide mem era, with the clamping arms secured to these slide members. Rams or jacks may be provided for moving the arms with the slide members traveling within the guides on movement of the arms.

With such a construction, the minimum practical spacing of the arms when they are retracted is determined to some extent by the length of the slide members and guides used in mounting the arms, and the length of the ram or rams that may be provided for producing extension and retraction. Arms that may be shifted a relatively large distance apart usually may not easily be shifted to a relatively close spacing, as when such is done the slide members used in mounting the arms extend an undesirable extent to the sides of the attachment, thus reducing the maneuverability of the fork lift truck that mounts the attachment. The rams also may introduce maneuverability problems. To overcome such deficiencies, it has been suggested that a pivoted outer arm section be provided for at least one of the arms, and that means be provided to pivot this outer arm section inwardly toward the opposite arm, with such pivoting producing a closer spacing between the ends of the arms than would otherwise be possible. Generally, this invention relates to improvements in such a construction that includes a pivoted arm section, with such improvements resulting in a more versatile and a more practical type of construction.

Among the disadvantages characterizing prior known constructions is the fact that there has been a lack of control over the arm that includes the pivoted arm section, more specifically a lack of control over that point in the arms movement where pivoting of the pivoted arm section starts. When the pivoted arm section is caused to pivot inwardly, because the end of the arm section moves at an accelerated rate, the clamping pressure that the end of the arm section can generate decreases. For optimum results, therefore, it is desirable that the pivoted arm section pivot only after the arm including the section has been moved as close as practically possible to the opposite arm. With such close spacing, load sizes (and weights) are at their smallest, and the decreased clamping pressure is not important. Another drawback of prior known constructions is that they have not permitted side shifting of a load, that is, they have not permitted, with the arms in any of their positions, a load to be clamped and then moved to one side by conjoint movement of both arms in the same direction. A feature of the construction of this invention is that both arms may be moved in unison on the frame mounting them, with the arms in any relative position, with the clamping pressure of the arms not relaxing, whereby side shifting is possible.

A general object of the invention, therefore, is to provide improved clamping mechanism including opposed clamping arms, which takes care of the above-indicated difficulties in a highly practical and satisfactory manner.

More specifically, it is an object of this invention to provide improved clamping mechanism, including opposed clamping arms, where at least one of the arms inciudes a pivoted outer section pivotable inwardly toward the other arm to produce clamping engagement, and such pivotal movement occurs as a result of the arm with the pivoted outer section moving within a predetermined distance of the opposed clamping arm, and irrespective of its exact position on the frame that mounts the arms.

Another object is to provide improved clamping mechanism having opposed clamping arms, Where at least one of the arms has a pivoted section as indicated above, and where the construction accommodates movement of both arms simultaneously in a given direction (to enable side shifting of a load) without relaxation of the clamping pressure exerted by the arms.

Another object is to provide a construction wherein a sliding element used in the mounting for one slidable clamping arm is operable to produce pivotal movement in a pivoted section provided in an opposed arm, with such sliding element coming into engagement with an abutment portion provided for the pivoted section, to produce the pivotal movement.

Y et another object is to provide an improved construction for clamping mechanism wherein the means for producing pivotal movement in the pivoted section of a clamping arm is protected from inadvertent damage, such means being shielded by structure encompassing the means throughout a wide range of movement of the arm. A still further object of the invention is to provide an improved construction for a clamping arm with a pivoted outer arm section, where the arm is relatively thin, and thus most easily slipped into a narrow space between closely adjacent loads.

These and other objects and advantages are attained by the invention, and the same is described hereinbelow in conjunction with the accompanying drawings, wherein:

FIG. 1 is a side elevation, with portions broken away, or one form of clamping mechanism as contemplated by this invention, such clamping mechanism in the embodiment illustrated taking the form of a paper roll grab, and including a pair of opposed clamping arms with pads or load' gripping means at their forward extremeties for clamping onto a roll of paper or similar cylindrical object;

FIG. 2 shows the underside of the upper clamping arm (or the arm including the pivoted section) in FIG. 1, with such arm in an extended position (or the position indicated in dashed outline in FIG. 1) and with portions of the arm broken away; and

FIG. 3 is a front elevation of portions of the mechanism shown in FIG. 1, as it would look with the load-clamping 3 arms spread apart or extended, and drawn on a somewhat smaller scale.

Referring now to the drawings, and first of all to PEG. 1, clamping mechanism in the form of a paper roll grab is indicated generally at iii. Clamping mechanism 1% comprises a pair of opposed load-clamping arms, indicated at 12 and 14, mounted on a frame 16, with arms 12, 1 extending out from the front of the frame.

The rear of frame 16 is attached to revolvable structure 18 of conventional construction, provided to enable rotation of the frame about a horizontal axis and swinging of the arms in such a manner as to upend or invert heavy cylindrical objects, such as paper rolls, clamped onto by the arms. Thus, the arms may be positioned to a position where one is above the other (as shown in FIG. 1) or to a position where they are on either side of each other, or to multiple other positions. Revolvable structure 13 includes a pair of circular plates 20, 22 containing bearing races (not shown) and mounted so that plate 22 is rotatable relative to plate 29. Within a casing 24 is provided mechanism (not shown) such as hydraulic motors or jacks for producing rotation of plate 22 relative to plate 29 and swinging of the arms as described. Brackets used in mounting structure 18 on a fork lift truck, more specifically the elevating mechanism of the truck whereby the entire clamping mechanism may be shifted up and down, are indicated at 26. Details of the truck, and revolvable structure 18, are not shown, as they are known structures and an explanation of the structures is not considered necessary for an understanding of the invention.

Frame 16 (now referring to FIGS. 1 and 3) comprises a first set of guide tubes or guide means 36a, E li/'1, and a second set of guide tubes or guide means 32a, 3212. Guide tubes 3%, 3012 are used in slidably mounting load clamping arm 14 for movement toward and away from arm 12, and guide tubes 32a, 3217 are used in slidably mounting load-clamping arm 12 for movement toward and away from arm 14. The various guide tubes are suitably rigidly secured together, by plate structure 34.

Load-clamping arms 12 and 14 are somewhat similar in construction, but differ in certain respects, and each will be described specifically.

Considering first load-clamping arm 14, and with reference now to FIGS. 1 and 2, the arm has a side profile which may be described as generally tapered, and includes a base or butt end 14a and a tip end 141'). The arm is mounted on frame 16 with its butt end adjacent guide tubes 39a, b. The load-clamping arm is an articulated arm, and comprises an inner arm section 46 and outer arm section 42 pivotally connected to the inner section.

Inner section includes a back wall 44 having arm carrier portions 46 extending rearwardly therefrom. The carrier portions are joined to elongated slides or guide elements 48 (see also FIG. 3) slidably mounted within guide tubes 39a, 3%. These slides move to and fro in guide tubes 39a, 3% on extension and contraction of arm 14. Elongated slots 50 along the forward sides of tubes 30a, 3012 (see FIG. 3) accommodate carrier portions 46 with the arm retracted within the outline of frame 16.

Further describing inner section 30, carried forwardly of back wall 44 and joined therewith are axially aligned and spaced-apart bearing portions 54. As will hereinafter be described, these bearing portions are part of the pivot means pivotally mounting outer section 42 on inner section 40.

Outer arm section 42 comprises outer and inner cover plates, indicated at 56, 58, respectively, spaced relatively close together so as to give a thin side profile to the arm. The plates diverge from each other progressing toward the butt end of arm 14. Plates 56, 58 are fastened to, and along forward portions of the plates are spaced apart by, side plates 60. Rear portions of plates 55, 58 are fastened to, and spaced apart by, side members 62, 64..

The pivot connection of the outer arm section to the 4 inner arm section is provided by journal portions such as portion 66 joined to the outer arm section and journaled within a bearing portion 54. Each journal portion is connected to the outer arm section by a cap 67 welded to the journal portions and secured to a side member by screws 68.

With arm 14 in a fully extended position, outer arm section 42 extends straight out, as shown by the dashed outline indicated for the arm section at 42A in FIG. 1. In this position, cover plate 56 abuts the top edges of webs 6? that connect back wall 44 and bearing portions 54, thus to prevent the arm section from pivoting upwardly or in a counterclockwise direction in FIG. 1. The arm section may be pivoted from this straight-out position, in a clockwise direction or downwardly in FIG. 1, to a position such as that shown in solid outline for the arm section in FIG. 1, where the rear edge of cover plate 58 engages bottom edges of webs 6'9. Movement in a clockwise direction from the straight-out position is resisted by a coiled torsion spring 70 mounted within the outer arm section 42.

More specifically, and referring again to FIG. 2, at 72 there is indicated a disc rotatably mounted on a journal portion 66 and having a cylinder section 74 joined thereto as by welding. Disc 72 is fastened to outer arm section 42, for movement conjointly therewith, by a pin 76 that extends through the disc and cover plate 58. Torsion spring 7i encircles cylinder section 74, and an end Tila of the torsion spring extends into disc 72 thus to be anchored in the disc. An end 7212 of the torsion spring, which is opposite end 72a, overlaps, and is held in place by a ledge 77 that is part of inner arm section 49. Cooperating with cylinder section 74 in centering the coil spring is a cylinder section 78 joined to disc similar to disc 72 adjacent the other side of the arm.

A pressure pad or load-gripping means 86 is connected by hinges 88 to the outer end of arm section 42. The pressure pad is contoured to fit about the usual load handled. Biasing means is provided for swinging the rear of the pressure pad into snug adjacency with the forward end of arm section 42, thus to reduce the overall side profile of the arm when the same is not in contact with a load. Such biasing means may take the form of sets of links 90 pivoted at one set of ends to pressure pad 86 and connected at their other sets of ends to plugs 92. Plugs 92 are slidable along the inner, convex surface of cover plate 58, with movement to the right in FIGS. 1 and 2 being resisted by coil springs 94.

Side member 64 of arm 14 has a projection 96 that extends rearwardly and into guide tube 32a with arm 14- in the contracted position shown in solid outline in FIG. 1. With arm 14 in an extended position, the projection is in alignment with guide tube 32a. The forward side of guide 32a is slotted, as at 98, whereby the projection can. move into tube 32a on movement of arm 14 from its extended to its retracted position; The projection constitutes an actuated portion movable in a path adjacent frame 16 and used in producing pivotal movement of outer arm section 42 after arm 14 reaches a predetermined spacing with respect to oppositely disposed arm 12.

Completing the description of arm 14, a motor means for moving the arm is indicated at 100 (see FIG. 3). As illustrated, the motor means comprises a fluid-actuated ram or jack of conventional construction. The cylinder portion of the ram is fixed on frame 16, and the rod 100a for the ram is secured to arm 14 through an extension 102 joined to back wall 44.

Considering now the construction of load-clamping arm 12, this arm also tapers progressing from a butt end adjacent frame 16 to a tip end disposed forwardly of the frame. The arm comprises cover plates 106, 108 spaced apart by and joined to side plates 110. In the embodiment illustrated, arm 12 is not an articulated arm, but instead a rigid arm comprising one section only. Side plates 110 are joined to a back wall 112, and the latter has carrier portions 1-14 secured thereto which are joined to elongated slides or guide elements 116 mounted within guide tubes 32a, 32b.

Slides or elements 116 are slidably mounted for reciprocal movement within guide tubes 32a, 32b. A bushing such as may be used in centering slide or element within a guide tube is indicated at 118. Accommodating carrier portions 114 when arm 12 is shifted toward arm 14 and to a retracted position are elongated slots 120 provided in the sides of guide tubes 32a, 32b.

Like clamping arm 14, arm 12 is provided with a pressure pad or load gripping means, indicated at 126. The latter is connected to the forward end of the arm '12 by hinges 128. [Biasing means 130, similar to the biasing means provided pad 86, is provided for pulling the back edge of the pressure pad snugly adjacent arm 12.

A motor means for shifting arm 12 as guided by tubes 32a, 32b is indicated at 1132, and comprises a ram or jack with the cylinder portion of the secured to frame 16 and its rod 132a connected in a suitable manner to arm 12.

It will be noted that slides or elements 116 used in mounting arm 12 project toward arm 14. When the two arms are shifted toward each other, upon reaching a predetermined spacing, the end of the element 116 within tube 32a comes into contact with projection 96 of arm 14-. The relative spacing between the arms when contact is first made is illustrated in FIG. 1, with reference to arm 12 as shown in solid outline, and the dashed outline for arm. 14 indicated at 14B. Upon further movement of the arms toward each other, the element 116 bears upon projection 96 and produces pivotal movement of outer arm section 4-2 with the outer end of the arm section swinging toward 12. Thus, by providing the projection positioned in the path of element 116, means is provided for producing automatic pivoting of the pivoted outer arm section upon the two arms reaching a predetermined relative spacing.

The construction contemplated makes possible the handlin g of rolls in a new and novel manner, as will now be explained. With the two arms in the position shown in solid outline in FIG. 1, outer arm section 42 has been swung toward arm 12, as it would be in the handling of small rolls. If ram or jack 100 connected to arm 14 were now extended, and ram or jack 132 connected to arm 12 were now retracted, the two arms shown in FIG. 1 would be caused to move conjo-intly upwardly on frame 16. Movement would be without pivotal movement of section 42. and relaxation of clamping pressure, if the rams were extended and retracted in unison at the same rate. If frame '16 were rotated to place the arms on their sides, such movement may be employed to produce side shifting of a load. Side shifting is also possible with the arms r spaced apart and outer section 42 in its straight-out position. This is an important feature of the invention, and made possible by reason of the fact that it is not the position of arm 14 relative to frame 16 that determines pivotin g of section 42, but instead the position of arm "14 rela tive to arm 12.

The construction contemplated also results in the production of maximum clamping pressures in various positions of the arms; When section 42 is caused to pivot inwardly, clamping pressure is reduced because of the accelerated movement occurring in its forward end. It should be noted, however, that such pivotal movement only occurs when the arms have reached a close spacing, and when as a consequence light loads are being handled. Arm 14 may occupy various positions on frame 16, and its outer arm section pivoted only when arm 14 is moved close enough thereto for element 116 to come against projection 96. In prior known constructions, where pivotal movement is determined by the position of an arm relative to the frame mounting it, pivot action may occur in the arm before close arm spacing is reached, with a reduction in clamping pressure occurring. Stating the concept in another way, the pivot movement is controlled whereby premature pivotal movement is prevented.

As another feature of the invention, it should be noted that the mechanism producing pivotal movement is positioned inwardly on the frame, and in most positions of the arms shielded by encompassing tube structure. Thus, parts are protected from damage or inadvertent actuation (important when operating conditions are considered).

The torsion spring producing straightening of the articulated is fully shielded, and the construction permits a thin side profile for the arm. The spring mechanism is relatively simple and trouble free in operation.

Various modifications and changes are possible in the construction of the clamping mechanism, without departing from the invention. It is desired not to be limited to the specific embodiment disclosed, but to cover all modifications and variations that would be apparent to one skilled in the art, and that come Within the scope of the appended claims.

It is claimed and desired to secure by Letters Patent:

1. In a clamping device for lift trucks and the like, a frame, a first clamping arm, a second articulated clamping arm comprising inner and outer sections hinged together, means mounting said arms on said frame with the arms oppositely disposed and spaced apart and extending out to one side of said frame and each movable toward the other, said outer section of said second clamping arm having a portion that moves in a path adjacent said frame on movement of the second clamping arm, said first clamping arm having a portion that moves in a path adjacent said frame on movement of the first clamping arm and that is out of engagement with said portion of said second clamping arm, said portions of said arms engaging each other upon the two clamping arms being moved toward each other to a predetermined minimum spacing and producing pivotal movement of said outer section on movement of the arms to a closer spacing than said predetermined spacing.

2. The device of claim: 1, wherein the means movably mounting said arms comprises for said first clamping arm an elongated tube, said portion of said second clamping arm comprises a portion movable in a path within said tube, and said portion of said first clamping arm comprises a slide portion also movable in a path within said tube.

3. In a clamping attachment for lift trucks and the like, a frame, a pair of oppositely disposed clamping arms, and means mounting said arms on said frame with the arms relatively movable toward and away from each other, said means mounting said arms including at least one elongated guide means and an element connected to one of said which is movable within said guide means, the other arm of said arms including a pivotally mounted outer section pivotable about an axis spaced outwardly from said frame and a portion integral with said outer section movable within said guide means, said portion engaging said element upon the arms moving toward each other and reaching a predetermined spacing, said element and said portion producing pivotal movement of said outer section upon the arms being moved to a spacing closer than said predetermined spacing.

4. In a clamping attachment for lift trucks and the like, a frame; a pair of oppositely disposed clamping arms; and means mounting the rear extremities of said arms on said frame with the forward extremities of said arms extending out from the frame and with the arms relatively movable toward and away from each other; said means mounting said arms including a first and a second parallelly disposed elongated guide means, a first element connected to one of said arms which is movable within one of said guide means, and a second element connected to the other of said arms which is movable within the other of said guide means; said other arm including a pivotally mounted outer section normally approximately paralleling said one and pivotable about an axis spaced outwardly from said frame toward said other arm; said outer section having a portion integral with the outer section movable within said one guide means; said portion engaging said first element movable within said one guide means upon the arms moving toward each other to a predetermined spacing; said element and said portion producing pivotal movement of said outer section upon the arms being moved to a spacing closer than said predetermined spacing.

5. In a clamping device for lift trucks and the like, said device including a frame and a pair of oppositely disposed and movable clamping arms mounted on said frame for movement between fully relatively extended and contracted positions, said arms including at least one arm which is an articulated arm and which comprises an inner section and an outer pivoted section; the improvement comprising a movable actuating part connected to the other of said arms; said actuating part being movable in a path to and fro on said frame conjointly with movement of said other arm; a movable actuated part connected to the pivoted section of said one arm and operable to produce pivotal movement of said pivoted section on openatively engaging said actuating part; said actuated part being movable to and fro in a path on said frame conjointly with movement of said one arm; said actuating and actuated parts being out of operative engagement with said arms in their fully relatively extended position; the paths of movement of said actuating and actuated parts coinciding and said parts moving into operative engagement on said one arm reaching a predetermined spacing away from saidrother arm regardless of the position of said other arm on said frame.

References Cited in the file of this patent UNITED STATES PATENTS 

1. IN A CLAMPING DEVICE FOR LIFT TRUCKS AND THE LIKE, A FRAME, A FIRST CLAMPING ARM, A SECOND ARTICULATED CLAMPING ARM COMPRISING INNER AND OUTER SECTIONS HINGED TOGETHER, MEANS MOUNTING SAID ARMS ON SAID FRAME WITH THE ARMS OPPOSITELY DISPOSED AND SPACED APART AND EXTENDING OUT TO ONE SIDE OF SAID FRAME AND EACH MOVABLE TOWARD THE OTHER, SAID OUTER SECTION OF SAID SECOND CLAMPING ARM HAVING A PORTION THAT MOVES IN A PATH ADJACENT SAID FRAME ON MOVEMENT OF THE SECOND CLAMPING ARM, SAID FIRST CLAMPING ARM HAVING A PORTION THAT MOVES IN A PATH ADJACENT SAID FRAME ON MOVEMENT OF THE FIRST CLAMPING ARM AND THAT IS OUT OF ENGAGEMENT WITH SAID PORTION OF SAID SECOND CLAMPING ARM, SAID PORTIONS OF SAID ARMS ENGAGING EACH OTHER UPON THE TWO CLAMPING ARMS BEING MOVED TOWARD EACH OTHER TO A PREDETERMINED MINIMUM SPACING AND PRODUCING PIVOTAL MOVEMENT OF SAID OUTER SECTION ON MOVEMENT OF THE ARMS TO CLOSER SPACING THAN SAID PREDETERMINED MINIMUM SPACING. 